[hardwired]

Depends on what you're doing. If you can't get four places because of decimal location or precision issues you can use double. For presentation you can use NumberFormat:

Code:

// see NumberFormat api for options.
NumberFormat nf = NumberFormat.getInstance();
nf.setMinimumFractionDigits(4);
nf.setMaximumFractionDigits(4);
String s = nf.format(myFloatValue);
// or, in j2se 1.5+ you can specify precision
s = String.format("%.4f", yourFloatValue);

DecimalFormat is another class that some use for this.